My invention pertains to a dual tone selector apparatus including an answerback signaling arrangement. More specifically, the invention relates to remote station code selector apparatus which includes a bandpass filter, compression amplifier network with a gated feedback circuit which actuates oscillation of the network to generate an answerback signal indicating the registration of a received control function.
The use of telephone selectors for the remote control of distant functions is well known in the supervisory control field. Since many such arrangements do not provide for the return of specific indications to the control point, it is desirable to have answerback signals to indicate to the operator that the transmitted control function has been received and registered. One form of such selectors uses audio frequency tones to transmit the selection code which chooses the remote station and/or the function to be controlled. Normally each code digit is represented by a pair of audio tones transmitted simultaneously. In these systems, it is highly desirable and more efficient to use an audio tone as the answerback signal. No special receiving apparatus is then needed at control location as the operator can hear the response. However, this requires an effective and efficient arrangement for generating the answerback signal.
Accordingly, an object of my invention is a telephone type selector system providing an audio frequency answerback signal.
Another object of the invention is a dual tone selector system with audio tone answerback for each remote station to indicate registry of a command function.
A further object of the invention is a dual tone selector, responsive to a code of successive tone pairs transmitted from a control office to select a control function when the proper code digits are received, which transmits an answerback tone to the office when the control code is received and registered.
Still another object of my invention is a code selector at a remote station responsive to the reception of a proper code sequence, each digit represented by a pair of audio frequency tones transmitted from a central location, to select the desired control function and to generate an audio tone answerback signal when the function selection is registered.
Yet another object of the invention is a telephone selector system for transmitting control functions to remote stations by means of digital codes, each digit of which is represented by a pair of audio frequency tones, each station selector responding to a preselected sequence of code digits to register the desired function and transmit an audio frequency answerback signal to the control location to indicate the registration of the transmitted function control.
A still further object of the invention is a dual tone selector, for use in a telephone selector system, which responds to the reception of a preselected code in the form of sequential pairs of audio frequency tones to register the selected function and to transmit an answerback audio frequency tone to the control office which transmitted the preselected code.
Another object of my invention is a dual tone selector, at a remote station of a telephone selector system, which includes a feedback circuit for the input bandpass filter and amplifier circuit network, enabled when a function transmitted from a control location is registered, to actuate the filter, amplifier network to generate an audio frequency answerback signal, within the bandpass range to indicate the registry of the function.
Other objects, features, and advantages of my invention will be apparent from the following specification and appended claims when taken with the accompanying drawings.